Largest study of mycotic aortic aneurysms shows EVAR is durable in most patients

20th January 2015

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A European multicentre analysis of 123 patients treated for mycotic aortic aneurysms with endovascular repair demonstrates this approach is feasible, with 91% survival at 30 days, and for most patients a durable option. The authors, however, also show that a significant number (19%) of fatal infection-related complications occur.

The study was published by Karl Sörelius et al in Circulation in December 2014, and the lead author was Anders Wanhainen, Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden.

“Mycotic aortic aneurysm is a rare but life-threatening disease, with an incidence of about 0.65–2% of all aortic aneurysms in western countries and reportedly higher in East Asia. The disease carries a very poor prognosis as mycotic aortic aneurysms have a tendency to grow rapidly and to rupture; patients with mycotic aneurysms often have severe comorbidities, in particular immunodeficiency, and coexisting sepsis,” the authors write. They add, “Conventional surgical treatment with resection of the aneurysm, extensive local debridement, and revascularisation by in-situ reconstruction or extra-anatomic bypass is the gold standard but carries a high mortality and morbidity. Furthermore, the anatomical location of the aneurysm sometimes makes surgical repair very demanding, or even impossible.”

EVAR for mycotic aneurysms may be considered either permanent or a bridge to open surgery, allowing the patient to recover before definitive elective open surgery, the investigators note. Today, only a few small single-centre studies with limited follow-up have been published. Therefore, they say, the crucial question of durability remains unanswered.

The aim of this European multicentre collaboration was to study the durability of EVAR in mycotic aneurysms by assessing the late infection-related complications and long-term survival.

All mycotic aneurysms treated with EVAR between 1999 and 2013 at 16 centres in eight European countries were retrospectively reviewed. In total, 123 patients with 130 mycotic aneurysms were identified and included in the study.

The mean age of the patients was 69 years (range 39–86), 71% were men, 47% had immunodeficiency, and 38% presented with rupture. The aneurysms were located in ascending aorta/arch (n=4), descending aorta (n=34), paravisceral aorta (n=15), infrarenal aorta (n=63), and multiple (n=7). Treatments were thoracic EVAR (n=43), fenestrated/branched EVAR (n=9), and infrarenal EVAR (n=71). The mean duration of antibiotic treatment was 30 weeks (range 1–420) and 32 patients (26%) had antibiotic treatment continuously throughout the study period. Eighty two patients (67%) were treated with multiple antibiotics.

The mean follow-up time was 35 months (1 week–149 months), and six patients (5%) were converted to open repair during this period. According to a Kaplan-Meier analysis, one-month survival was 91%, one-year 76%, five-year 55%, and 10-year 41%.

A total of 33 patients (27%) developed an infection-related complication, of whom 23 (70%) died (19% of the total cohort). Thirty per cent (7/23) of these occurred within the first 30 days, 52% (12/23) within 90 days, and 82% (19/23) within one year. Four patients had a fatal infection-related complication after one year; one endograft infection after 16 months, one graft enteric fistula after 35 months, one new mycotic aneurysm after 36 months, and one sepsis after 54 months. In nine of the patients, a fatal recurrent infection-related event occurred after discontinuation of antibiotic treatment. The cumulative incidence of infection-related death, with death of other causes as competing risk was 16.4% at one year, 21.7% at five years, and 21.7% at 10 years.

Presence of SalmonellaIn a Cox regression model, all-cause mortality was significantly associated with age (p=0.033) and non-Salmonella positive blood culture (p=0.015), while a negative association was seen for negative blood culture (p=0.042). Within the group of non-Salmonella positive blood culture, the survival was similar for Staphylococcus, Streptococcus, and miscellaneous organisms. The five-year survival of patients with non-Salmonella positive blood culture was 41%, with infection-related complications as the cause of death in 50% (14/28) of which nine (64%) occurred after 90 days. In the subgroup of 15 patients with Salmonella positive blood culture, four out of six deaths occurred within 90 days, and the five-year survival among those surviving 90 days was 90%.

The authors also found that the five-year survival of patients with immunodeficiency was 40%, with infection-related complications as the cause of death in 64% (16/25) of which nine (56%) occurred after 90 days. The subgroup of 12 patients with periaortic/intrathrombus gas on preoperative CT scan had a five-year survival rate of 36%—all deaths were infection-related of which four (67%) occurred after 90 days.

The investigators comment: “Mycotic aneurysm is a complex disease with challenging treatment and poor survival. The largest study of open surgical treatment of mycotic aneurysms was published in 2011 by Yu and colleagues from Taiwan and consisted of 54 patients and the largest study on endovascular treatment, published in 2012 by Sedivy et al from the Czech Republic, included 32 patients. The disease is difficult to study because of its rarity, therefore large-scale multicentre collaborations are necessary.” They add that this European multicentre study of mycotic aneurysms is the largest ever and the aims were to assess the durability of endovascular treatment, including late reinfection.

The authors summarise the findings of this study: 1) good short-term outcome (91% survival at 30 days), 2) a significant number (19%) of fatal infection-related complications, mostly occurring during the first postoperative year, 3) a relatively good long-term outcome (55% survival at five years) with few serious late infection-related complications, and 4) adverse long-term outcome among those with a non-Salmonella positive blood culture.

“Most reports on open repair show a much worse outcome, with short-term mortality rates of 20–40% and significant short- and long-term morbidity related to the operation. Reports on long-term outcome after open repair are scarce. The reported two-year survival is about 60% and a five-year survival rate of 35% was reported from a German single-centre study on 33 patients,” the authors write. “Late graft infections occurred in 7–10% of the cases and extra-anatomic bypass had worse outcome than in-situ reconstructions. A minimally invasive approach by means of endovascular techniques makes it possible to treat patients unsuitable for major open surgery. In this report a majority of the patients had severe, multiple comorbidities, hostile anatomy, ongoing sepsis or presented with rupture. A similar case mix was not seen in previous reports on open repair, making comparison difficult.”

They conclude: “Endovascular treatment of mycotic aortic aneurysms is feasible and for most patients a durable treatment option. Late infection-related complications do occur, are often lethal, and warrant long-term antibiotic treatment and follow-up, especially in patients with non-Salmonella positive blood culture. In those cases, EVAR could be considered a palliative option or a bridge to later elective open repair.”